Burglar alarm



Dec. 26, 1922.

M. J. CAWLEY.

BURGLAR ALARM.

HLED MAY 12, I919.

2 SHEETS-SHEET I.

fnaen (or Dec. 26, 1922.

2 SHEETS-SHEET 2.

M. J. CAWLEY.

BURGLAR ALARM. FILED MAY12, 1919.

Patented ec. 26, 1922.

STATES thaws Mam BURGLAR ALARM.

Application filed May 12, 1919. Serial to. 296,361.

To all whom it may concern:

Be it known that 1, MICHAEL J. CAWLEY, a citizen of the United States, residing in Bronx Borough, New York city, in the county of Bronx and State of New York, have invented certain new and useful Improvements in Burglar Alarms, of which the following is a specification.

This invention relates to alarms for protecting doors of residences, bank vault doors, cash registers, money drawers, etc., and par ticularly for the doors of apartments.

Doors and the like have heretofore been provided with alarms which have been successfully manipulated and silenced by burglars. Other alarms have been such that they could be readily cut out from the'door by the burglar. Still other varieties have been such as to be readily overcome in different ways. v

One of the main objects of my'invention is to provide a simple, durable, inexpensive device, readil'yapplicable to the door or drawer, and easily understood and operated, to make it practically impossible for an unauthorized person to open it without giving warning, and to prevent the operation of the alarm from being checked. A

To this end, I mount upon the exterior of the door, drawer, or the like, a dial for co-operation with an index, to control an alarm. The occupant of the apartment may set the index to a point upon the dial which is known only to the occupants of the apartment; and when the index is so set,'the door may be opened without setting off the alarm.

Hence the occupants of the apartment may go in and out freely. The last one to leave the apartment, however, turns the index away from said point. The effect of this is to set the alarm so that it will go off when the door is next opened. This will happen at anypoint to which the index may be set (except the original point above referrechto), so that any intruder attempting to open the door, either by a key or by forcing it, is sure to set off the alarm. If the intruder attempts to adjust the index to its single neutral point, he can have no way of knowing whether his guess is right, without opening the door, and the opening of the door sets off the alarm. When the occupant of the apartment returns, he may set the index to the'neutral point, and open the door in= dependently of the alarm.-

In order to forestall a cautious thief who may take opportunity to note the neutral position of the indexfroin day to da*, and thereby gain a clue asto just where the index should be set before attempting to open the door, means are provided whereby the position of the neutral point may be changed at'will. While this makes it necessary for the occupant to remember any new numher to which the index may be set, still it also renders the expectant house-breaker uncertain, since, although he may have observed the index at the same point on the dial for several days,*still he has no way of being surethat the dead point has not been changed since his last observation. He therefore would run great risk in attempting to open the door, and obviously his caution I would lead him to conclude that the risk is too great to take; whereby the'very fact of the adj ustability of the neutral'point is itself asafeguard.

Moreover, in the preferred manner of practicing the invention, the alarm may be independently disconnected within the apartment' at will, thus rendering: it feasible to have the index or dial'always set ofigfrom the neutral point, thereby misleading the reconnoitering thief. In practicing the invention according to this method, the last occupant to depart would only need to reconnect the alarm within the apartment,before leaving. Upon returning, he could set the alarm to the neutral point before opening the door; andafter entering the apartment he could again disconnect the alarm, and immediately set the index or dial off from the neutral point, making it impossible for others to learn which point on the dial is neutral.

Another important feature of the invention resides in means for preventing the intruder from stopping the ringing or operation of the alarm. A bell may be employed, and provision is made whereby when the door is opened, the bell will begin to ring and continue to ring until the source of power is exhausted, notwithstanding the efforts the intruder may use to stop the ring ing. He may cut or tear out. the wires; he may rip the dial mechanism off from the door; but still the bell will ring. For this purpose there is used, in addition to themain- I circuit which includes the bell and the door, an auxiliary circuit for bell ringing pur- 110 poses, preferably for ringing the same bell; and this auxiliary circuit, which is normally open, is automatically closed by the opening of the door, and remains closed. This auxiliary circuit mechanism may bein another room, and securely hidden from search by the housebreaker.

Said auxiliary circuit may be closed by a magnet, and the magnet may be electrically connected to the door in such a way that when the door opens the magnet will be energized and operate to close said auxiliary circuit; and the auxiliary circuit remains closed, even though the magnet which closed it becomes tie-energized, and hence the bell must ring continuously.

If the alarm should be off accidentally by an occupant, he may readily open "the auxiliary circuit. After being broken, the auxiliary circuit will remain open until the door is again opened by an intruder.

Other features and advantages will hereinafter appear.

In the accompanying drawings,

Fig. l is a diagrammatic view of the electric circuit of my improved alarm apparz tus; v

Fig. 2 a vertical section showing a fragment of the door shown in Fig. l and illustratingthe method ofapplying my invention thereto;

Fig. 3 a front elevation of the electrical mechanism viewed from the inside of the door;

Fig. 4 a detail face view of the dial and index for opening and closing the main alarm circuits; and,

Fig. 5 a view showing one form of switch closing shaft and key therefor, and the key provided with an indexv The alarm bell is placed in an electrical circuit 21. which is normally open at two points, one point being at the top or other part of the door or drawer 22 which is to be protected, and the other point being at the dial switch. Considering first the door, it will be seen in Figure 1 that a wearing plate 23 set'into the top of the door may noi'inallv hold up a slide 24- against the tension of a compression spring 25, the slide and spring being contained in a suitable housing 26 which is easily mounted in the lintel 27. The slide is in the form of a round bar havmg opposite guide pins 29. When the door opens, the spring presses the slide down, and said guide pins 29 serve as a bridge, inasmuch as they strike terminals in the form of opposite yielding brass or copper strips 31 fastened to the 'lower edge of the lintel. This completes the main bell circuit at this point, so that the opening of the door starts the bell ringing if the circuit has been also closed at the dial.

Secured to the outer side of'the door by screws-33 is a'dial plate 34, having, for ilwasher d8 by'fingers at lustration, sixteen subdivisions; and in front of said dial turns an index 35, to which may be attached for convenience a thumb wheel 36. This thumb wheel is fixed upon a central shaf 37 whereby it adjusts or controls a circuit-closing linger 38, the latter being swiveled upon the inner end, of said shaft at 39 and held by a dran sprin -10 against a metal, disk 41, forming the other terminal of the switch. This spring 40 may beattached at one end to an arm 42 extending from the shaft. This spring enables the circuit-closing or contact finger 38 to yield and ride easily and quietly over any obstructions or rough surfaces upon the disk 4i. or at the neutral point 4-5-1 therein, and no indication of the neutral or circuit-breaking point can therefore be gained by the house-breaker by listening while he turns the knob. In the disk ll is formed a gap at the neutral point 43, and

the gap is filled with vulcanite 44: or other non-conducting material, which is flush with the face of the terminal disk ll. so that the contact finger 38 may ride lightly, smoothly and soundlessly over both the disk and the insulating material.

When the index 35 has been adjusted to such a point that the spring contact finger 3S rests upon the insulating material 44, the bell circuit 21 stands open at this point, and the door may therefore be opened freely without ringing the hell, even though the circuit does become closed at the lintel; while closing the door, of course, reopens the circuit at the lintel.

The dial'mechanism also comprises a plate i5, which is secured by screws to against the inner face ol the door, the shaft 37 tending through this plate and through a other insulating disk 47, which is spacedfrom the door plate in by a cylinder or washer 48 of slightly yielding insulating material. Disk 47 is held against said secured by screws 50, said fingers bent over the outer face of the insulating disk. One of the bell circuit wires may be attachedby nuts 51 to a stem 52 extending from the'brass disk 41 through the insulating disk 47, and the otherof said wires may be caught by one of the door plate screws d6, so that'the current passes through the door plate and the shaft 37 to the circuit-closing finger 3S thereon, and

thence through the disk 47 and the stem 52 is sufiicient to retain the disk 47 wherever adjusted, and the same is accessible to the user, who may turn the disk at any time, and may then turn :the knob .36 until the circuit-closing finger 38 rests upon the insulating material 44 in the gap, and may then note and remember where the index 35 stands upon the dial 234. door, he may turn the index 35 to some other point, thus closing the switch 38, 41, and insuring that the bell will ring in case'the door is opened. Upon his return he reset the index to the known dead point,

so that the door may be opened without sounding the alarm.

It will be seen that the mechanism is simple, durable, not liable to get out of order, and is readily applied to the door even by an unskilled person.

hen the door is opened, the circuit closer 24 slides ofl from the top of the door, and is forced down by its spring until the pins 29 thereon engage the terminals 31, thereby closing the alarm-circuit at this point. If at this time the finger 38 rests upon any part of the circuit-closing disk 41, the electric circuit is completed through the mains 21 to the battery 58 and the bell 20, thereby setting the latter to ringing.

The intruder will naturally close the door, expecting to stop the ringing; but to forestall this action and prolong the ringing of the alarm indefinitely, there is provided a magnet 54, which is energized at the closing of said main circuit 21, and operates a switch lever 57, thereby to effect the ciosing of an auxiliary bell-ringing circuit 56. This auxiliary circuit 56 preferably rings the same bell 20, and extends from the battery 53 through said switch lever 57, bell 20, and thence back to the battery or other source of power. From the foregoing it will be seen that the alarm is not silenced by the closing of the door; in fact, the entire apparatus at the door may be destroyed without stopping the ringing of the bell once it has begun; so that the alarm will continue until the battery is exhausted or the switch lever 57 moved into inoperative position. I I

It will therefore be seen that the complete closing of the circuit at the door has the effect of sending a current through the main circuit to ring the bell, and also through the coil of magnet 54 to operate the switch-lever 57, which closes the auxiliary or independent bell-ringing circuit 56,

and that the hell can only be stopped by operating the lever 57 to break saidauxiliary circuit. The magnet 54 and the lever 57 will be securely hidden from the intruder The friction caused by the Upon closing the and its location will be known only to the occupants of the apartment, that attempts of the intruder to check thealarm will be-baffled. c

Any attempt of the intruder, after opening the door, to stop the bell by raising the slide 24 would prove unavailing, since .ihe auxiliarv circuit 56 has become "closed.

and the bell device continues in operation independently of the. main circuit, thus making it of no consequence whether the latter is broken or not. w a

' There maybe provided in the main cir-c cuit 21 a circuit-breaking switch 62, which may be closed at night and opened during the day, when people are apt to be stirring about in the apartment; so that it usually becomes unnecessary for anybody coming in the door during waking hours to pay any attention to the dial andindex 85. Hence at such times the index may be placed in some false position, so that the reconnoitering thief" would be misled. But at night the circuit may be closed, and the full protectlon of the device secured. The same thing may also be done durlng the day, by

the last occupant to leave the apartment,

a device as the index 35 already described,

there may be used a key 68, Figure 5, having a nib 64 to enter a slot 65 in the end of the adjusting shaft 37', whereby the lat ter may be rotated to an extent determined by an index 66 carried upon the key itself, and preferably foldable alongside thereof for compactness, being pivoted thereto at 67. Where a key is used, a thief will be unable to ascertain what point on the dial had been selected as the neutral point.

Variations may be resorted to within the scope of the invention, and portions of the improvements may be used without others.

Having thus described my invention, 1 claim:

1. In an electric alarm circuit, a circuit controlling device comprising a shaft, a body of insulating material mounted on said shaft, an adjustable contact disk mounted on said body and encircling said shaft and provided at a predetermined point with a surface of non-conducting material, a current conducting member pivotally mounted to said shaft and movable over the face of shaft, an adjustable contact disk mounted 1 on said body and encircling said shaft and movided ate. predetermined point with :1 SIUTfi UIG of non-conducting material, a current conducting member pivotally mounted t0 said shaft and movabie over the face 01? said disk to control the circuit through said disk, means for holding said member in enc-ngagement with said disk, and means in- X'OiVlHg adial and incheator for eontrolhng the movement of said shaft and the member pivoted thereto, whereby an authorized 10 party may set said member on the n0nc0nducting surface of said disk.

MICHAEL J. CAVVLEY.

Witnesses CATHERINE A. NEWELL, JENNIE P. THORNE. 

